1. Field of the Invention
The invention relates to lawn sprinklers, and more specifically, the invention relates to an electro-mechanical system for determining the moisture content of the soil for manual watering and for controlling lawn sprinkler systems.
2. Background of the Invention
In the past, it has been a well known practice to provide automatic watering devices, such as sprinklers, in order to supply plants with a proper amount of moisture so that the plants or natural growth will flourish. by providing a plant with too little or too much water, its growth progresses or life span will be impeded. Since the proper amount of moisture varies not only among different types of growth, but with the particular environment in which the plant is growing, it is time consuming process to manually supply the necessary water. Automatic or manual devices for providing the necessary water to the plant life are highly desirable and time saving devices.
For example, a conventional system employs a timer controller which operates a solenoid valve incorporated into a water system so that when the time as arbitrarily set by the user arrives, power is supplied via the solenoid to the water supply valve so that water is then supplied to a system of sprinklers or other irrigation devices. However, water may be supplied even though the ground or plant medium is saturated such as subsequent to a heavy rain or the like.
Therefore, a long standing need is present to incorporate into automatic water sprinkling systems, a detection device or apparatus which functions in conjunction with the timer to operate the water supply valve in response to the moisture content of the soil or plant medium.
U.S. Pat. No. 2,906,952 to Horecky discloses a device for measuring and regulating moisture content of soil comprising a by-pass circuit, separate from a primary circuit, and which by-pass circuit includes a probe or the like adapted to be easily inserted into the ground so that the degree of resistance to passage of electricity through the soil and through the by-pass circuit, and the extent of its conductivity may be measured and visually indicated on a meter of the device. A neon light is used to provide a visual signal.
U.S. Pat. No. 3,114,243 to Winters discloses an automatic system of agricultural irrigation comprising a moisture sensing probe, having an indicator. The indicator includes a needle which is pivoted for rotation about a center of a dial indicating the percentages of moisture at the tip of the probe. The probe is modified by providing a cover over the needle of a transparent insulating material which has a hole in the center coaxial with the pivot axis of the needle. A stop arm of a conductive material is mounted so that it intercepts the travel of the needle as the needle moves from one percentage indication to another.
U.S. Pat. No. 3,867,837 to Malin discloses a moisture detector comprising a container surrounding a detection area with a channel leading out of the container, a member connected in the channel with a portion of the member inside the container and a portion of the member outside the container, and a switch connected adjacent the distal end of the portion of the member lying inside the container. The change in weight of the member changes the position of the distal end of the portion of the member lying inside the container to activate the switch to signal a variation in the moisture content of the soil surrounding the portion of the member lying outside the container.
U.S. Pat. No. 4,055,200 to Lohoff discloses a soil moisture detector incorporated between a timer controller and an electrical water supply valve. The detector includes a pneumatic diaphram apparatus whereby a pressure level is maintained or released between a pair of diaphram in response to a moisture sensing valve buried in the ground. The pneumatic condition of the detector opens or closes a switch to supply voltage to the water supply valve.
U.S. Pat. No. 4,253,606 to Johnson discloses a spring loaded mechanism which opens the valve when released by a water sensitive element which monitors the moisture of the ground. A closing mechanism, which is actuated by water flowing through the valve automatically resets the spring loaded opening mechanism and closes the valve after a fixed quantity of water flow.
The instant invention is designed to overcome the problems and difficulties with prior art watering and automatic moisture supplying devices which are obviated by the present invention.